Khoury, JF;
Rettie, AJE;
Robredo, I;
Krogstad, MJ;
Malliakas, CD;
Bergara, A;
Vergniory, MG;
... Kanatzidis, MG; + view all
(2020)
The subchalcogenides Ir₂In₈Q (Q = S, Se, Te): Dirac semimetal candidates with re-entrant structural modulation.
Journal of the American Chemical Society
, 142
(13)
pp. 6312-6323.
10.1021/jacs.0c00809.
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Abstract
Subchalcogenides are uncommon compounds where the metal atoms are in unusually low formal oxidation states. They bridge the gap between intermetallics and semiconductors, and can have unexpected structures and properties because of the exotic nature of their chemical bonding, as they contain both metal-metal and metal-main group (e.g. halide, chalcogenide) interactions. Finding new members of this class of materials presents synthetic challenges, as attempts to make them often result in phase separation into binary compounds. We overcome this difficulty by utilizing indium as a metal flux to synthesize large (mm scale) single crystals of novel subchalcogenide materials. Herein, we report two new compounds Ir2In8Q (Q = Se, Te) and compare their structural and electrical properties to the previously reported Ir2In8S analogue. Ir2In8Se and Ir2In8Te crystallize in the P42/mnm space group and are isostructural to Ir2In8S but also have commensurately modulated (with q-vectors q = 1/6a* + 1/6b* and q= 1/10a* + 1/10b* for Ir2In8Se and Ir2In8Te, respectively) low temperature phase transitions, where the chalcogenide anions in the channels experience a distortion in the form of In-Q bond alternation along the ab plane. Both compounds display re-entrant structural behavior, where the supercells appear on cooling but revert to the original subcell below 100 K, suggesting competing structural and electronic interactions dictate the overall structure. Notably, these materials are topological semimetal candidates with symmetry-protected Dirac crossings near the Fermi level, and exhibit high electron mobilities (~1500 cm2 V-1 s-1 at 1.8 K) and moderate carrier concentrations (~1020 cm-3) from charge transport measurements. This work highlights metal flux as a powerful synthetic route to high quality single crystals of novel intermetallic subchalcogenides.
| Type: | Article |
|---|---|
| Title: | The subchalcogenides Ir₂In₈Q (Q = S, Se, Te): Dirac semimetal candidates with re-entrant structural modulation |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/jacs.0c00809 |
| Publisher version: | https://doi.org/10.1021/jacs.0c00809 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Anions, Metals, Crystal structure, Chalcogenides, Transition metals |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10093663 |
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